Hydraulic props



April 27, 1965 F. TOWN HYDRAULIC PRoPs 3 Sheets-Sheet 1 Filed July 2.1963 INV ENT OR Ffa/JK 75W 2 l., J nu n @MIM ATTORNEYS F. TOWN HYDRAULICPROPS April 27, 1965 3 Sheets-Sheet 2 Filed July 2, 1963 BY W n/rmATTORNEYS April 27, 1965 F. rowN HYDRAULIC PROPS v2' Sheets-Sheet 3Filed July 2, 19625 A'ITORNEY5 United States Patent O HYDRAULIC PROPSFrank Town, Burton Joyce, England, assigner to W. E. & F. Dobson LimitedFiled .luly 2, 1963, Ser. No. 292,274 Claims priority, application GreatBritain, July 31, 1962,

This invention relates to a hydraulic pit prop of the type having acrank-operated internal pump and releasevalve and, more particularly,where the crank mechanism has a pump handle which requires one arcuatemovement for operating the pump and a second arcuate movement foroperating the release valve.

It is known to provide an air valve for supplying air during theextension of ythe prop by operation of the pump and releasing air duringcontraction of the prop by operation of the release valve. However,prior art air valves have not been entirely satisfactory, since they aresubject to the entry of foreign matter, which reduces their eiliciency.This is especially true when the prop is laid downas when it is not inuse.

An object of the invention is to provide the prop with improved airvalve means whereby the prop is able to operate etciently for a longperiod.

Other objects and advantages of the invention may be seen in thedescription and operation of a specilic embodiment, which is describedwith reference to the accompanying drawings, in which- FIG. l is ageneral sectional view of a hydraulic pit prop equipped with air valvemeans according to the invention;

FIG. 2 is a side sectional view in enlarged scale of an upper part ofthe prop showing the air valve means;

FIG. 3 is a eros-sectional view through the air valve means with thevalve parts in the position they adopt during pumping up of the prop;

FIG. 4 is a similar view to FIG. 2 showing a pump handle tted and thevalve parts in the position they adopt during tluid valve releasecontraction of the prop; and

FIG. is a view similar to FIG. 3 but with the valve parts in theposition of FIG. 4.

Referring to FG. 1, the hydraulic prop shown is of the type referred tohaving an internal pump 1 and release valve 2 which are operable by acrank mechanism indicated generally 3. The crank 3 includes a crank axle4 which, at its outwardly-projecting end (see FlG. 2), is formed with atransverse hole 4a for insertion of a pump handle 5 (FIGS. 3-5). Thepump handle 5 goes through a predetermined arc of movement to operatethe pump 1 and a second arc of movement to operate the release valve 2.

More specically, the prop comprises a lower pressure cylinder 6 and anupper, reservoir-forming, hollow ram 7. The pump 1 is housed in thelower end of the ram 7 and has an associated check valve 8 through whichfluid can be pumped from the ram 7 into the cylinder 6. The pump piston1a is connected by a rod 9 to a crank 1i) secured to the crank axle 4.

The release valve 2 is also housed in the lower end ot the ram 7 and isconnected by a rod 11 to a projection 12 on the -rod 9 by means of alost motion slot 11a.

As shown in FIG. 2, the crank axle 4 is connected by a collar 13 to thecrank 10. Further, the axle 4 has a central bore 14 forming at its innerend an air chamber 15 open to the interior of the ram` 7. The bore 14also has an intermediate reduced diameter bearing part 16 and an outerend further reduced diameter bearing part 17 open to the transverse hole4a.

The crank axle 4 is mounted in a bearing sleeve 18 which is secured bywelding to the ram 7. The sleeve 1@ ICC Patented Apr. 27, 1965 pinacross the bore 14, to partly project into the transverse hole 4a.

The intermediate reduced diameter bearing part 16 of the bore 14provides a shoulder 16a against which sealing is effected by a sealingring 26 on the plunger 23 behind the shoulder 23a.

The plunger -23 is also formed with an annular air passage 27substantially in the same general transverse or radial plane as that ofthe transverse air communication passage 22 and the outer air outlet 19.

When the prop is not in use, the crank axle 4 and air valve parts are asshown in FIG. 2, i.e., before the pump handle is tted, so that theplunger 23 partly projects into the transverse hole 4a, the sealing ring26 seals against the shoulder 16a, and the outer air outlet 19 is cutoir" from the annular air passage 27.` With the parts in vthis position,there is little or no possibility of 4foreign matter passing from theouter air outlet 19 into the in-terior of the valve. Even when the propis laid on the ground, the outer air outlet 19 is guarded to `someextent by the enlarged part 4b of the crank axle 4, and should foreignmatter enter the outer air outlet'19, it cannot pass into the interiorof the valve. Further, dirt can be readily cleared out of the outer air.outlet 19 before the prop is p-ut into use. By this means the air valvehas a desirably long and efficient working life. Y

Operation When the prop is in use, the pump handle 5 is fitted so thatthe plunger 23 is pressed in, as shown in FIG. 4. Thereupon, the sealingring 26 becomes spaced from the shoulder 16a, and the annular airpassage 27 provides communication between the transverse aircommunication passage 22 and the air chamber 15. However, at this stage,as illustrated in ysolid line in PIG. 3, the transverse aircommunication passage 22 does not register with the outer air outlet 19.Instead, as shown in FIG. 3, during the time that the pump handle 5 isoperated in its ypredetermined -arc of movement to operate the pump 1,the

transverse air communication passage 22 is carried around with the crankaxle 4 through an arc of movement during which it is out of registrywith the outer air outlet 19. This pumping action causes a comparativelysmall displacement of the uid and consequently ysmall displacement ofair takes place by passage of air between the plunger 23 and the crankaxle bore 14.

When it is required to contract the prop, the pump handle is movedthrough a second arc of movement during which it operates the releasevalve 2, and during this movement, as shown in FlG. 5, the handle 5turns the crank axle 4 to a position in which the transverse aircommunication passage 22 registers with the outer air outlet 19.Therefore in this position of the parts, the comparatively largedisplacement of iluid is accompanied by similar large `displacement ofair which is drawn into the prop. The air drawn into the'prop owsthrough the crank axle bore l14, the annular air passage 27, thetransverse air communication passage 22, and the lregistering outer airoutlet 19.

After contraction of the prop and it it is not required kfor immediatereuse, the handle is turned back to the initial pumping position wherethe transverse air com- 3 municationpassage 22 .is again moved out ofregistry with the outer air outlet 19, thereby preventing thepossibility of foreign matter entering into the valve.

What I claim is:

l. A hydraulic jack, comprising a cylinder, a reservoirproviding rammounted in said cylinder, a pump and release valve mounted in said ram,passage means coupling said pump and ram, and second passage meanscoupling said ram and said reservoir, said release valve beingpositioned in said second passage means, a bearing sleeve fixed to andextending throughthe wall of said reservoir', a crankshaft journaled insaid sleeve and having a crank portion within said reservoir coupled tosaid pump and release valve, said crankshaft having a portion outsidesaid reservoir adapted to receive a pump handle, said shaft having anaxial bore in the shaft portion intermediate the outside and crankportions thereof and communicating with said reservoir, saidintermediate sha-ft portion being adapted to pass air from lsaidreservoir to the outside thereof, a seat in said bore, a slidevalve insaid axial bore adapted to be engaged and unseated by said handle whensaid handle is received in said shaft outside portion, said intermediateshaft portion being equipped with a transverse passage communicatingwith said bore outward of the seat of said slide valve, said sleevebeing equipped with a transverse passage located so as to align withsaid shaft transverse passage only during the release valve openingposition of said shaft. Y Y

2. The structure of claim l in which. said shaft outside portion isequipped with an integral annular enlargement projecting radially beyondsaid sleeveitransverse passage whereby said sleeve transverse passage isprotected against entry of dirt.

meegaan 3. A hydraulic jack, c-omprising a cylinder, areservoirproviding ram mounted in said cylinder, a pump and releasevalve mounted in said ram, passage means coupling said pump and ram, andsecond passage means coupling said ram and said reservoir, said releasevalve being positioned in said `second passage means, a crankequippedshaft rotatably mounted in said reservoir and projecting exteriorlythereof, -said crank including means for coupling said shaft to saidpump and release valve to actuate said pump during a predetermined arcof rotation of said shaft and thereafter operate said release valve uponfurther shaft rotation, said shaft being equipped with a bore extendinggenerally axially at least partway therethrough and communicating withsaid reservoir, slide valve means in said bore, said shaft, in theportion thereof projecting exteriorly of said reservoir, being equippedwith a handle-receiving slot, said slot and slide valve means being soarranged tha-t insertion of a handle in said slot actuates said slidevalve means, and rotary valve means opera-bly associated with said shaftand so arranged therewith that movement of said shaft for actuating said.release valve also actuates said rotary valve means.

References Cited by the Examiner UNITED STATES PATENTS 686,133 11/01Yost Z22- 385 1,212,757 l/l7 Freese 60-52 1,344,919 6/20 Marr 60--523,055,626 9/62 Tebb et al 60-52 X Y JULIUS E. WEST, Primary Examiner.'

1. A HYDRAULIC JACK, COMPRISING A CYLINDER, A RESERVOIRPROVIDING RAMMOUNTED IN SAID CYLINDER, A PUMP AND RELEASE VALVE MOUNTED IN SAID RAM,PASSAGE MEANS COUPLING SAID PUMP AND RAM, AND SECOND PASSAGE MEANSCOUPLING SAID RAM AND SAID RESERVOIR, SAID RELEASE VALVE BEINGPOSITIONED IN SAID SECOND PASSAGE MEANS, A BEARING SLEEVE FIXED TO ANDEXTENDING THROUGH THE WALL OF SAID RESERVOIR, A CRANKSHAFT JOURNALED INSAID SLEEVE AND HAVING A CRANK PORTION WITHIN SAID RESERVOIR COUPLED TOSAID PUMP AND RELEASE VALVE, SAID CRANKSHAFT HAVING A PORTION OUTSIDESAID RESERVOIR ADAPTED TO RECEIVE A PUMP HANDLE, SAID SHAFT HAVING ANAXIAL BORE IN THE SHAFT PORTION INTERMEDIATE THE OUTSIDE AND CRANKPORTIONS THEREOF AND COMMUNCATING WITH SAID RESERVOIR, SAID INTERMEDIATESHAFT PORTION BEING ADAPTED TO PASS AIR FROM SAID RESERVOIR TO THEOUTSIDE THEREOF, A SEAT IN SAID BORE, A SLIDE VALVE IN SAID AXIAL BOREADAPTED TO BE ENGAGED AND UNSEATED BY SAID HANDLE WHEN SAID HANDLE ISRECEIVED IN SAID SHAFT OUTSIDE PORTION, SAID INTERMEDIATE SHAFT PORTIONBEING EQUIPPED WITH A TRANSVERSE PASSAGE COMMUNICATING WITH SAID BOREOUTWARD OF THE SEAT OF SAID SLIDE VALVE, SAID SLEEVE BEING EQUIPPED WITHA TRANSVERSE PASSAGE LOCATED SO AS TO ALIGN WITH SAID SHAFT TRANSVERSEPASSAGE ONLY DURING THE RELEASE VALVE OPENING POSITION OF SAID SHAFT.